200931774 九、發明說明 【發明所屬之技術領域】 本發明係關於用在機器人關節的中空致動器。 【先前技術】 產業用機器人已在汽車生產線取代人力作業之汽車組 裝和其他零件組裝等、或是與人共同進行作業的情形漸增 〇 。而進行這種組裝作業時，除了要求機器人進行複雜的動 作，還要求至今尙未實現的轉入動作和較大的可動範圍。 又，由於必須配置多數機器人進行作業，而要求縮小設置 範圍，從目前已有的將各臂藉由基端關節使其動作的機器 人、到將各臂藉由配置在各關節的致動器使其動作的像人 的手腕動作的機器人，逐漸受到期待。 爲了實現這種機器人，必須有可在臂內配線使電纜露 出在機器臂的框架外側而不產生與外界之干涉的構造，如 © 以往將馬達和減速機之組合配置在關節部時，爲了處理電 纜就會產生關節部變大之問題。因此期待有利用致動器內 部進行配線的中空致動器。 以往的中空致動器提案有將軸做成中空軸的AC伺服 馬達和減速機構所構成者（例如，參照專利文獻1及專利 文獻2)。利用第2圖說明以往的中空致動器。在波動齒 輪裝置101的減速機框架111內側，透過軸承12設有杯 狀的輸出軸113,在輸出軸113內側設有圓形花鍵114。 又，在減速機框架111端面固定著設在可撓性旋轉筒115 -4- 200931774 一方端部的磁場鐵芯部151，而設在另一方端部附近的外 齒116係卡合在圓形花鍵114。波形軸承117接觸在可撓 性旋轉筒U5內側，且設定成從波形軸承117傳遞轉矩。 波形軸承117係固定在馬達軸121，該馬達軸121係將後 述的馬達102所產生的轉矩輸入波動齒輪裝置1〇1，馬達 軸121的一方端係透過軸承118而支撐在輸出軸113內側 。又，減速機框架111的端面固定著磁場鐵芯（Field 〇 core) 132’磁場鐵芯132設有杯狀的中空軛131，係透過 空隙插入在可撓性旋轉筒1 1 5內側。中空軛1 3 1內側固定 著旋轉檢測器104的固定部141，固定部141內側固定著 旋轉部142隔著空隙相對向的馬達軸121。磁場鐵芯132 的另一端面固定著圓筒狀的馬達框架122，馬達框架122 內側固定著固定子125，係由具備電樞繞線123的環狀之 固定子鐵芯124所構成。固定子125內側設有旋轉子127 ，係具備構成馬達102的勵磁的永久磁鐵126，永久磁鐵 Ο 126係隔著空隙而與固定子鐵芯124相對向，且固定在馬 達軸121所固定的杯狀的馬達軛128。框架122的反輸出 側端面固定著第2托架105，係透過突出在托架1〇5內側 所設的外殼部152所設的軸承153’而支撐馬達軸121的 另一方端。具備與馬達1〇2的極數同一極數之制動器1〇3 的旋轉側永久磁鐵1 3 3係以在圓周方向等間隔地且鄰接的 磁極爲異極之方式，被固定在杯狀之馬達軛128內周，且 馬達102的永久磁鐵126的磁路形成共有狀態。在圓周上 以等間距著磁的環狀永久磁鐵所構成的旋轉側永久磁鐵 -5- 200931774 1 3 3之內側，隔著空隙將固定側永久磁鐵1 3 4 105的外殼部152。 又，第3圖表示內插有電磁制動器的中空 達202係由固定在框架201的定子221和杯 222所構成。中空軸203係固定在框架201， 器204固定在其周圍。位置檢測器205係由安 2 03的角度檢測用之磁氣感測器25 1和固定在 〇 反負荷側之角度檢測用磁鐵252所構成。減速 結合在轉子222的波形發電機271、固定在框 曲形花鍵72、旋轉自如地被支撐著的圓形花泰 成。輸出磁場鐵芯部係形成中空構造，兼作 209的支撐部。此外，轉子222係由高速側軸 〇 以上已說明的中空致動器可應用於機器人 專利文獻1 :日本專利實開平7-422 1 5號 G 頁、第1圖） 專利文獻2:日本專利特開2006-149 1 39 3頁、第1圖） 【發明內容】 將這種中空致動器應用到產業用機器人的 動器必須具備制動器。即，當工場停電或進行 姿勢保持時，若不具備制動器就無法獲取正確 有安全性上的問題。 固定在托架 致動器。馬 形狀的轉子 將電磁制動 裝在固定軸 轉子222的 機207係由 架201的撓 I 273所構 高速側軸承 承209支撐 的關節部。 公報（第3 號公報（第 關節時，致 原點位置之 姿勢，因此 -6- 200931774 以往的中空致動器具備與永久磁鐵相對向的電磁制動 器，而成爲藉由永久磁鐵間的吸引力保持位置的機構。這 種機構的情形，由於可利用非接觸使制動器發揮作用，因 此具有不因制動器產生粉塵問題的優點，相反地，一旦旋 轉速度變高則除了永久磁鐵間的磁吸力之外，還有渦電流 使制動器力發揮作用，因此制動器力變大。因此產生制動 器力對應速度而變化之問題。又，由於停止中係藉由永久 © 磁鐵間的磁吸力保持，因此當較該磁吸力大的外力發揮作 用時，將產生位置變動之問題。 本發明係鑑於如此之問題而硏發者，其目地在於提供 可縮短軸長並可使制動器確實地發揮作用以應用於機器人 的關節部的中空致動器。 爲了解決上述問題，本發明採用下述之控制方式。 申請專利範圍第1項記載的發明係中空致動器，其係 由馬達部、減速機部、制動器部、及旋轉位置檢測部所構 © 成，傳遞旋轉的軸係形成中空形狀，前述馬達部和前述制 動器部被配置在同一室者。 申請專利範圍第2項記載的發明，係前述中空致動器 爲從負荷側依序配置減速機部、馬達部、制動器部、旋轉 檢測部，前述馬達部和前述制動器部被配置在同一室者。 申請專利範圍第3項記載的發明，係兼用前述制動器 部和前述旋轉位置檢測部的磁場鐵芯者。 申請專利範圍第4項記載的發明係中空致動器，其係 由馬達部、減速機部、制動器部、及旋轉位置檢測部所構 200931774 成，傳遞旋轉的軸係形成中空形狀，前述制動器部係於磁 場鐵芯配置有制動器線圈，以相對向於前述制動器線圈的 方式配置有電樞，前述旋轉位置檢測部係於前述磁場鐵芯 配置有偵測器，以相對向於前述偵測器的方式配置有狹縫 式基板和LED，且前述磁場鐵芯兼用凸緣者。 申請專利範圍第5項記載的發明，係前述制動器部爲 在磁場鐵芯配置有制動器線圈，以相對向於前述制動器線 Ο 圈的方ά配置有電樞，前述電樞被配置成位在前述馬達部 端部近旁者。 申請專利範圍第6項記載的發明，係前述馬達部的電 樞繞線爲在馬達部被進行末端處理，通過前述制動器部的 磁場鐵芯之開口部而拉出電纜者。 申請專利範圍第7項記載的發明係中空致動器，其係 由馬達部、減速機部、制動器部、及旋轉位置檢測部所構 成，傳遞旋轉的軸係形成中空形狀，前述馬達部和前述制 © 動器部被配置在同一室，在前述減速機部及編碼器部爲了 不使來自前述制動器部的粉麈混入而藉由隔離手段予以分 離者。 申請專利範圍第8項記載的發明，係前述減速機部和 前述馬達部及前述制動器部之隔離手段爲利用側板進行者 〇 根據申請專利範圍第1至8項記載的發明，藉由將馬 達部和制動器部配置在同一室，兼用固定制動器部和編碼 器部的方式構成，可提供軸長較短的中空致動器。又，以 -8- 200931774 在制動器部利用電樞和電樞之摩擦的制動手段的方式，可 獲得確實之制動。 藉由獲得這種中空致動器而可配置在機器臂的各關節 ，獲得如人腕的動作。又，當工場停電或進行原點復歸之 姿勢保持時，可容易地保持正確姿勢。再者，由於藉由機 械式摩擦力獲得制動力，因此對於來自外部的力量亦可制 動，而可獲得確實之制動器。 【實施方式】 以下，參照圖面說明本發明之實施形態。 實施例1 第1圖表示本發明之實施形態之側面剖視圖。1爲馬 達部、2爲永久磁鐵' 3爲定子軛、4爲電樞繞線、5爲旋 轉子軛、6爲軸承、7爲油封、8爲波形插塞、9爲減速機 部、1〇爲輸出軸、11爲制動器部、12爲制動器線圈、13 爲電樞、14爲磁場鐵芯、15爲中空軸、16爲編碼器部、 1 7爲LED、18爲狹縫式基板、19爲偵測器。 馬達部1和減速機部9係被油封7分離。又，馬達部 1和編碼器部16也因制動器線圏12的固定構件安裝著編 碼器部16而被分離。馬達部〗和制動器部u被配置在同 一室。 藉由這種構成’在制動時產生的來自制動器部11的 微小粉麈’不會混入減速機部9及編碼器部16。又，藉 200931774 由制動器部11的磁場鐵芯兼用編碼器部1 6的偵測器1 9 之支撐構件的方式，進行零件共通化，而成制動器襯片 13配置在馬達部1的端面之構成。藉由這種構成，獲得 可縮短中空致動器軸長之構造。 接著，說明有關各部之構成。馬達部1係由永久磁鐵 2所構成，該永久磁鐵2係以隔著空隙相對向於捲繞在定 子軛3的電樞繞線4的方式配設在旋轉子軛5。旋轉子軛 〇 5係安裝在中空軸15，中空軸15係由軸承6以旋轉自如 的方式支撐，利用對電樞繞線4通電的方式進行旋轉者。 又，電樞繞線4係被末端處理，通過制動器部11的開口 部連通到外部者。 接著，說明有關減速機部。減速機部9係由波形軸承 91、圓形花鍵92、撓曲形花鍵93所構成。在中空軸15 連結有波形插塞8，在波形插塞8結合有波形軸承91。又 ’撓曲形花鍵93係固定在框架。撓曲形花鍵93外周具備 e 旋轉自如地被支撐著的圓形花鍵92。中空軸15之旋轉係 藉由結合在中空軸15的波形插塞8而傳遞到波形軸承91 ，被進行撓曲形花鍵93和圓形花鍵92之齒數差分減速， 從輸出軸10取出。 接著，說明有關制動器部。制動器部1 1係由制動器 線圈12和電樞14、制動器襯片13和未予圖示之制動彈 簧所構成。制動器襯片13係連結在中空軸15，與中空軸 1 5 —起旋轉。使其制動時，在制動器線圈1 2通電則推迫 力在制動彈簧發揮作用，以電樞1 4和制動器襯片1 3接觸 -10- 200931774 的方式產生制動力。如此地使其接觸進行制動的方式，可 確實地制動。 接著，說明有關編碼器部。編碼器部16係由LED17 和狹縫式基板1 8、偵測器19所構成。狹縫式基板1 8係 與中空軸15連結，在狹縫式基板18形成有用於透過光的 狹縫。以挟持該狹縫式基板18的方式配置LED17和偵測 器1 9，將LED17的光藉由偵測器1 9受光以檢測旋轉位置 ❹ 接著，說明關於制動器部11的粉塵影響。制動時利 用在電樞1 4和制動器襯片1 3間產生摩擦的方式而獲得制 動力。因此時的摩擦而從各構件產生數微米（V )大小的 摩耗粉。該磨耗分爲制動器襯片13的摩擦板係由樹脂系 膜壓、半金屬或燒結合金所構成，電樞14係由碳鋼所構 成，而由硬度低的電樞13的摩擦板產生者。相對於此， 定子軛3和永久磁鐵2間的空隙爲0.3mm~0.5mm程度， 〇 相較於發塵的摩耗粉，即使摩耗粉混入仍具備充分空隙， 因此發塵的影響爲極低者。例如，摩耗粉混入減速機部9 時，在圓形花鍵和撓曲形花鍵間成爲摩耗粉造成齒面損傷 的原因。又，摩耗粉混入編碼器部16時，成爲LED光產 生亂反射的原因。因此，爲了縮短中空致動器的軸長，係 將馬達部1和制動器部11內包在同一室而構成者。 【圖式簡單說明】 第1圖係本發明的中空致動器之側面剖視圖。 -11 - 200931774 第2圖表示第1習知例之側面剖視圖。 第3圖表示第2習知例之側面剖視圖。 【主要元件符號說明】 1 :馬達部 2、126 :永久磁鐵 3 :定子軛 © 4、123 :電樞繞線 5 :旋轉子軛 6、118、153:軸承 7 :密封件 8 :波形插塞 9 :減速機部 10 :輸出軸 1 1 :制動器部 © 1 2 :制動器線圈 1 3 :制動器襯片 14 :電樞 1 5 :中空軸 1 6 :編碼器部 17 : LED 1 8 :狹縫式基板 1 9 :偵測器 9 1 :波形軸承 -12- 200931774 92 、 114 、 273 :圓形花鍵 93、272 :撓曲形花鍵 1 〇 1 :波動齒輪裝置 102 :馬達 103 :制動器 104 :旋轉檢測器 105 :托架 〇 111 :減速機框架 112： 1 13 :輸出軸 1 1 5 :可撓性旋轉筒 1 1 6 :外齒 1 1 7 :波形軸承 1 2 1 :馬達軸 122 :馬達框架 〇 124 :固定子鐵心 125 :固定子 1 2 7 :旋轉子 1 2 8 :馬達軛 13 1 :中空軛 132、151 :磁場鐵芯 1 3 3 :旋轉側永久磁鐵 1 3 4 :固定側永久磁鐵 141 :固定部 -13- 200931774 142 ： :旋轉部 1 52 ： 外殻部 22 1 ： 定子 222 : 轉子 251 ： 磁氣感測器 252 ： 角度檢測用磁鐵 271 ： ❹ 波形發電機 -14-200931774 IX. Description of the Invention [Technical Field of the Invention] The present invention relates to a hollow actuator for use in a robot joint. [Prior Art] Industrial robots have been increasingly used in automobile production lines to replace manual assembly of automobile work and other parts, or to work together with people. In this assembly operation, in addition to requiring the robot to perform complicated operations, it is required to perform a transition operation that has not been realized so far and a large movable range. In addition, since it is necessary to arrange a plurality of robots to perform work, and it is required to reduce the setting range, the robots that have been operated by the base joints from the existing arms are arranged to be arranged by the actuators of the respective joints. The robot that acts like a human wrist is gradually expected. In order to realize such a robot, it is necessary to have a structure in which the cable can be wired inside the arm to expose the cable outside the frame of the robot arm without interfering with the outside, as in the case where the combination of the motor and the reducer is conventionally arranged in the joint portion, in order to handle The cable will cause problems with the joints becoming larger. Therefore, it is expected to have a hollow actuator that uses the inside of the actuator for wiring. In the conventional hollow actuator, there is proposed an AC servo motor and a speed reduction mechanism in which a shaft is a hollow shaft (see, for example, Patent Document 1 and Patent Document 2). A conventional hollow actuator will be described with reference to Fig. 2 . Inside the reduction gear frame 111 of the pulsation gear unit 101, a transmission output shaft 113 is provided through the bearing 12, and a circular spline 114 is provided inside the output shaft 113. Further, the magnetic field core portion 151 provided at one end portion of the flexible rotating cylinder 115-4-200931774 is fixed to the end surface of the speed reducer frame 111, and the external teeth 116 provided near the other end portion are engaged in a circular shape. Spline 114. The wave bearing 117 is in contact with the inside of the flexible rotating cylinder U5 and is set to transmit torque from the wave bearing 117. The wave bearing 117 is fixed to a motor shaft 121 that inputs a torque generated by a motor 102, which will be described later, into the wave gear device 1〇1, and one end of the motor shaft 121 is supported by the bearing 118 and supported inside the output shaft 113. . Further, a field core 132 core is fixed to the end surface of the speed reducer frame 111. The magnetic field core 132 is provided with a cup-shaped hollow yoke 131, and is inserted into the inside of the flexible rotating cylinder 1 15 through a gap. A fixing portion 141 of the rotation detector 104 is fixed to the inside of the hollow yoke 1 31, and a motor shaft 121 in which the rotating portion 142 faces the gap is fixed to the inside of the fixing portion 141. A cylindrical motor frame 122 is fixed to the other end surface of the magnetic field core 132, and a stator 125 is fixed to the inside of the motor frame 122, and is constituted by an annular stator core 124 having an armature winding 123. A rotor 127 is provided inside the stator 125, and a permanent magnet 126 constituting the excitation of the motor 102 is provided. The permanent magnet 126 126 is opposed to the stator core 124 via a gap, and is fixed to the motor shaft 121. Cup-shaped motor yoke 128. The second bracket 105 is fixed to the opposite-side end surface of the frame 122, and the other end of the motor shaft 121 is supported by a bearing 153' provided by the outer casing portion 152 provided inside the bracket 1〇5. The rotating side permanent magnet 1 3 3 having the same number of poles as the number of poles of the motor 1〇2 is fixed to the cup-shaped motor so as to be equidistant in the circumferential direction and adjacent to each other. The inner circumference of the yoke 128 and the magnetic path of the permanent magnet 126 of the motor 102 form a common state. The outer casing portion 152 of the side permanent magnet 1 3 4 105 is fixed to the inner side of the rotating side permanent magnet -5-200931774 1 3 3 which is formed by an annular permanent magnet which is magnetized at equal intervals on the circumference. Further, Fig. 3 shows that the hollow 202 in which the electromagnetic brake is inserted is constituted by the stator 221 and the cup 222 fixed to the frame 201. The hollow shaft 203 is fixed to the frame 201, and the device 204 is fixed around it. The position detector 205 is composed of a magnetic gas sensor 25 1 for angle detection of an 203 and an angle detecting magnet 252 fixed to the 〇 counter load side. The deceleration is combined with a wave generator 271 coupled to the rotor 222, a circular flower fixed to the frame-shaped spline 72, and rotatably supported. The output magnetic field core portion forms a hollow structure and also serves as a support portion for 209. Further, the rotor 222 is a high-speed side shaft. The hollow actuator described above can be applied to a robot Patent Document 1: Japanese Patent Laid-Open No. Hei 7-422 No. 5, No. G, No. 1) Patent Document 2: Japanese Patent OP-2006-149 1 39 3, FIG. 1) SUMMARY OF THE INVENTION The actuator for applying such a hollow actuator to an industrial robot is required to have a brake. That is, when the factory is powered off or posture is maintained, it is impossible to obtain the correct safety problem without the brake. Secure to the bracket actuator. The horse-shaped rotor The machine 207 that mounts the electromagnetic brake to the fixed-shaft rotor 222 is a joint portion supported by the high-speed side bearing 209 of the frame 201 of the flexible shaft 273. Bulletin (No. 3 (When the joint is in the position of the origin position, -6-200931774, the conventional hollow actuator has an electromagnetic brake that faces the permanent magnet, and is held by the attraction force between the permanent magnets. Mechanism of position. In the case of such a mechanism, since the brake can be utilized by non-contact, there is an advantage that the dust problem is not caused by the brake, and conversely, once the rotation speed becomes high, in addition to the magnetic attraction between the permanent magnets, Further, the eddy current causes the brake force to function, so that the brake force becomes large, so that the brake force changes depending on the speed. Further, since the stop is maintained by the magnetic attraction between the permanent magnets, the magnetic force is relatively higher. When a large external force acts, a problem of positional change occurs. The present invention has been made in view of such a problem, and its object is to provide a joint portion which can shorten the axial length and enable the brake to function reliably for application to the joint portion of the robot. Hollow actuators. In order to solve the above problems, the present invention adopts the following control method. The hollow actuator according to the first aspect of the invention is the motor unit, the speed reducer unit, the brake unit, and the rotational position detecting unit. The shaft that transmits the rotation forms a hollow shape, and the motor unit and the motor unit are In the invention according to the second aspect of the invention, the hollow actuator is configured such that a speed reducer unit, a motor unit, a brake unit, and a rotation detecting unit are disposed in order from the load side, and the motor unit and the motor unit are disposed. The invention described in claim 3 is the same as the magnetic field core of the brake portion and the rotational position detecting portion. The invention described in claim 4 is hollow-actuated. The motor unit, the speed reducer unit, the brake unit, and the rotational position detecting unit are configured as 200931774, and the shaft for transmitting rotation forms a hollow shape, and the brake portion is provided with a brake coil in the magnetic field core to face each other. An armature is disposed in the brake coil, and the rotating position detecting unit is provided with a detector in the magnetic field core In the invention according to the fifth aspect of the invention, in the brake device, the brake coil is disposed in the magnetic field core. An armature is disposed on a side of the brake coil, and the armature is disposed in the vicinity of the end of the motor portion. The invention according to claim 6 is the electric motor of the motor unit. The pivoting wire is a motor that is subjected to end processing in the motor portion, and the cable is pulled out through the opening of the magnetic field core of the brake portion. The hollow actuator according to the seventh aspect of the invention is a motor portion. The speed reducer unit, the brake unit, and the rotational position detecting unit are configured to have a hollow shaft shape, and the motor unit and the actuator unit are disposed in the same chamber, and the speed reducer unit and the encoder unit are configured to The powder from the brake portion is not mixed and separated by means of isolation. According to the invention of the eighth aspect of the invention, the method of separating the reduction gear unit, the motor unit, and the brake unit is performed by a side panel, and the motor unit is used according to the invention described in claims 1 to 8. The brake unit is disposed in the same chamber as the fixed brake portion and the encoder portion, and a hollow actuator having a short shaft length can be provided. Further, in the case of -8-200931774, the braking means using the friction between the armature and the armature in the brake portion can obtain a reliable brake. By obtaining such a hollow actuator, it is possible to arrange the joints of the robot arm to obtain an action such as a human wrist. Also, when the factory is powered off or the posture of the return-to-origin is maintained, the correct posture can be easily maintained. Further, since the braking force is obtained by the mechanical friction force, the force from the outside can be braked to obtain a reliable brake. [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Embodiment 1 Fig. 1 is a side cross-sectional view showing an embodiment of the present invention. 1 is a motor part, 2 is a permanent magnet '3 is a stator yoke, 4 is an armature winding, 5 is a rotor yoke, 6 is a bearing, 7 is an oil seal, 8 is a wave plug, 9 is a speed reducer part, 1〇 The output shaft, 11 is the brake part, 12 is the brake coil, 13 is the armature, 14 is the magnetic field core, 15 is the hollow shaft, 16 is the encoder part, 17 is the LED, 18 is the slit type substrate, 19 is Detector. The motor unit 1 and the speed reducer unit 9 are separated by an oil seal 7. Further, the motor unit 1 and the encoder unit 16 are also separated by the encoder unit 16 attached to the fixing member of the brake coil 12. The motor portion and the brake portion u are disposed in the same chamber. The fine powder 来自 from the brake portion 11 which is formed during the braking is not mixed into the speed reducer unit 9 and the encoder unit 16. Further, in 200931774, the magnetic field core of the brake unit 11 and the support member of the detector 19 of the encoder unit 16 are used to share the components, and the brake lining 13 is disposed on the end surface of the motor unit 1. . With this configuration, a structure capable of shortening the axial length of the hollow actuator is obtained. Next, the configuration of each unit will be described. The motor unit 1 is composed of a permanent magnet 2 which is disposed on the rotor yoke 5 so as to be wound around the armature winding 4 of the stator yoke 3 with a gap interposed therebetween. The rotary yoke 〇 5 is attached to the hollow shaft 15, and the hollow shaft 15 is rotatably supported by the bearing 6, and is rotated by energizing the armature winding 4. Further, the armature winding 4 is end-treated and communicates with the outside through the opening of the brake portion 11. Next, the speed reducer unit will be described. The reduction gear unit 9 is composed of a wave bearing 91, a circular spline 92, and a flex spline 93. A wave plug 8 is coupled to the hollow shaft 15, and a wave bearing 91 is coupled to the wave plug 8. Further, the 'flexive spline 93' is fixed to the frame. The outer periphery of the flexible spline 93 is provided with a circular spline 92 that is rotatably supported by e. The rotation of the hollow shaft 15 is transmitted to the wave bearing 91 by the wave plug 8 coupled to the hollow shaft 15, and the differential number of the flex spline 93 and the circular spline 92 is decelerated and taken out from the output shaft 10. Next, the brake portion will be described. The brake portion 1 1 is composed of a brake coil 12, an armature 14, a brake lining 13, and a brake spring (not shown). The brake lining 13 is coupled to the hollow shaft 15 and rotates together with the hollow shaft 15 . When braking, when the brake coil 12 is energized, the pushing force acts on the brake spring, and the braking force is generated in such a manner that the armature 14 and the brake lining 13 contact -10-200931774. In such a manner that it is brought into contact with the brake, it can be reliably braked. Next, the encoder unit will be described. The encoder unit 16 is composed of an LED 17 and a slit substrate 18 and a detector 19. The slit substrate 18 is connected to the hollow shaft 15, and a slit for transmitting light is formed in the slit substrate 18. The LED 17 and the detector 19 are disposed so as to hold the slit substrate 18, and the light of the LED 17 is received by the detector 19 to detect the rotational position. Next, the influence of the dust on the brake portion 11 will be described. Braking is obtained by friction between the armature 14 and the brake lining 13 during braking. Therefore, frictional particles of several micrometers (V) are generated from the respective members by friction. The friction plate which is divided into the brake lining 13 is composed of a resin film, a semi-metal or a sintered alloy, and the armature 14 is made of carbon steel and is produced by a friction plate of the armature 13 having a low hardness. On the other hand, the gap between the stator yoke 3 and the permanent magnet 2 is about 0.3 mm to 0.5 mm, and the 〇 phase has a sufficient gap compared with the dust-absorbing powder, even if the powder is mixed, so that the effect of dust generation is extremely low. . For example, when the friction powder is mixed into the speed reducer unit 9, the tooth surface damage is caused by the abrasion powder between the circular spline and the flex spline. Further, when the abrasion powder is mixed into the encoder portion 16, the LED light is caused to cause disorder. Therefore, in order to shorten the axial length of the hollow actuator, the motor portion 1 and the brake portion 11 are enclosed in the same chamber. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a side cross-sectional view showing a hollow actuator of the present invention. -11 - 200931774 Fig. 2 is a side cross-sectional view showing the first conventional example. Fig. 3 is a side sectional view showing a second conventional example. [Description of main component symbols] 1 : Motor section 2, 126: Permanent magnet 3: Stator yoke © 4, 123: Armature winding 5: Rotating yoke 6, 118, 153: Bearing 7: Seal 8: Wave plug 9 : Reducer unit 10 : Output shaft 1 1 : Brake part © 1 2 : Brake coil 1 3 : Brake lining 14 : Armature 1 5 : Hollow shaft 1 6 : Encoder part 17 : LED 1 8 : Slit type Substrate 1 9 : Detector 9 1 : Wave bearing -12- 200931774 92 , 114 , 273 : Round spline 93 , 272 : Flexing spline 1 〇 1 : Wave gear device 102 : Motor 103 : Brake 104 : Rotation detector 105: Bracket 〇 111: Reducer frame 112: 1 13 : Output shaft 1 1 5 : Flexible rotating cylinder 1 1 6 : External gear 1 1 7 : Wave bearing 1 2 1 : Motor shaft 122: Motor Frame 〇 124 : stator core 125 : stator 1 2 7 : rotator 1 2 8 : motor yoke 13 1 : hollow yoke 132, 151 : magnetic field core 1 3 3 : rotating side permanent magnet 1 3 4 : fixed side permanent Magnet 141: fixing portion-13-200931774 142 : : rotating portion 1 52 : outer casing portion 22 1 : stator 222 : rotor 251 : magnetic gas sensor 252 : magnetic for angle detection 271: ❹ waveform generator -14-